A typical peristaltic pump includes a compressible tube for carrying a fluid. The tube generally has an upstream inlet, a downstream outlet and a curved portion oriented in a horseshoe-like or circular path. The curved portion is typically supported on its outermost surface against a curved stationary surface such as the interior wall of an enclosure for the pump. Near the upstream inlet, a rotor-mounted (or cage-mounted) roller engages and progressively squeezes the tube against the surface. The squeezing force is of sufficient magnitude to at least partially compress and generally occlude the internal passage of the tube. This occlusion is carried around the curved portion by the roller, forcing fluid ahead of the occlusion toward the downstream outlet portion of the tube. As fluid ahead of the occlusion is discharged through the downstream outlet, the expansion or restitution of the tube in the wake of the occlusion creates a suction that draws in more fluid through the upstream inlet, and the cycle repeats.
The unique pumping properties of peristaltic pumps make them ideally suited for certain applications. For example, peristaltic pumps are widely used in applications where constant metering of fluids at relatively low flow rates is desired; applications requiring the fluids being pumped to remain free of contamination; applications requiring the fluid path to remain clean or sterile; and applications where corrosive, caustic or hazardous fluids must be pumped without the fluid directly contacting any components of the pump mechanism other than the tubing. Despite these advantages, conventional peristaltic pumps suffer drawbacks, one being complexity of the pumping mechanisms with many separate parts and attendant difficulty in replacing tubing.
The tubing is an expendable component. Due to contamination and/or wear and tear during normal use, the tubing is typically replaced several times over the life of a pump. In applications requiring sterility, the tubing may be replaced after each use. Unfortunately, replacement of tubing in conventional pumps can be a time-consuming and frustrating task that is highly conducive to error. Typically, the replacement process entails removal of screws that secure a front panel of a housing, removal of the housing, removal of the old tubing and careful installation of a new tubing. While each of these steps may present difficulty and consumes considerable effort and time, the step of installing the new tubing is usually the most difficult and fraught with risk. The new tubing must be properly aligned within a narrow space between compression rollers and a housing wall. Typically, this space is extremely difficult to access. Excessive stretching or improper alignment of the tubing risks premature failure of the tubing. Likewise, ramming the tubing into the narrow space using a screwdriver or other tool risks physical damage compromising the structural integrity of the tubing.
An entire pumping mechanism or rollers may also require replacement periodically for maintenance or to accommodate a specific pumping application. Illustratively, a roller may fail due to normal wear and tear over time. As another example, a rotor having three rollers may need to be replaced with a roller having two rollers to achieve a determined pumping rate. Unfortunately, however, conventional peristaltic pumps do not facilitate tool-free access to, removal and replacement of rollers or an entire pumping mechanism. Instead, such tasks typically require use of one or more tools, handling of small loose fastening parts (e.g., snap rings, nuts, bolts, screws and the like), and a considerable investment of time and attention. Loss of any part or lack of a required tool precludes or delays the necessary maintenance.
Thus, a peristaltic pumping mechanism is needed that greatly facilitates replacement of tubing, and/or replacement of rollers, and/or replacement of an entire pumping mechanism, without tools and without loose small parts. The tubing and roller locations should be easy to access for removal and installation. The housing for the pumping mechanism should be configured for readily opening and securely closing without the need for tools. Once the housing is opened, the tubing and rollers should be readily removable without the need to remove other components of the pumping mechanism. Concomitantly, the entire pumping mechanism should be easily replaceable, without a need for tools.
Accordingly, a need exists for a peristaltic pump having a pumping mechanism that includes an improved removable cover configured to facilitate access to a replaceable tubing and rollers, wherein the entire pumping mechanism, rollers and tubing may be replaced without use of tools and without a plurality of small loose parts. The invention is directed to overcoming one or more of the problems and solving one or more of the needs as set forth above.